1. Field of the Invention
The present invention relates to dispensing guns for fluid materials and, more particularly, to a dispensing gun incorporating a double reduction gear for extruding highly viscous materials.
2. Description of the Prior Art
Dispensing guns for highly viscous materials must generate extreme amounts of pressure to the material. This is especially true of conventional industrial epoxy guns. Such guns typically accept twin cylinder cartridges which separately contain the epoxy bonding agent and resin. The gun is operated to drive the bonding agent and resin to one end of the cartridge where the materials are combined and are extruded outward through an extended nozzle. In commercial applications, the nozzle typically comprises a thin tube with an interior arrangement of foils to provide a convoluted, internal passageway for the combined materials. As the epoxy materials are forced through the convoluted nozzle, the foils ensure that the resin and bonding agent are properly mixed before being ejected. However, the pressure needed to drive the epoxy materials through the convoluted nozzle is extreme.
For this reason, the prior art epoxy dispensing guns inevitably employ a motorized or pneumatic drive system.
For example, U.S. Pat. No. 4,583,934 issued to Hata et al. shows a rack and pinion type electric drive system for extruding fluid material from a nozzle 11. The rack and pinion assembly employs a reduction type gear assembly for increasing torque derived from the electric motor.
Similarly, U.S. Pat. No. 4,669,636 issued to Miyata shows an electric dispensing gun which employs a motor and clutch for selectively driving a rack and pinion type piston assembly.
Various pneumatic counterparts are also known to exist.
Unfortunately, electric guns often cannot be operated in the field without a portable generator. Pneumatic guns cannot be operated without a compressor. The guns themselves necessarily incorporate costly precision pneumatic or electrical parts which are inordinately expensive to manufacture. Such constraints render the guns completely useless for many field applications and expensive and impractical for others.
Clearly, there would be great advantages in a manually operated dispensing gun which is capable of developing sufficient force to dispense highly viscous materials such as, for instance, epoxy materials from a conventional twin cylinder epoxy cartridge.